The medical device industry produces a wide variety of electronic and mechanical devices for treating patient medical conditions. Depending upon medical condition, medical devices can be surgically implanted or connected externally to the patient receiving treatment. Clinicians use medical devices alone or in combination with drug therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best, and sometimes the only, therapy to restore an individual to a more healthful condition and a fuller life. One type of medical device that can be used is an Implantable Neuro Stimulator (INS).
An INS generates an electrical stimulation signal that is used to influence the human nervous system or organs. Electrical contacts carried on the distal end of a lead are placed at the desired stimulation site such as the spine and the proximal end of the lead is connected to the INS. The INS is then surgically implanted into an individual such as into a subcutaneous pocket in the abdomen. The INS can be powered by an internal source such as a battery or by an external source such as a radio frequency transmitter. A clinician programs the INS with a therapy using a programmer. The therapy configures parameters of the stimulation signal for the specific patient's therapy. An INS can be used to treat conditions such as pain, incontinence, movement disorders such as epilepsy and Parkinson's disease, and sleep apnea. Additional therapies appear promising to treat a variety of physiological, psychological, and emotional conditions. As the number of INS therapies has expanded, greater demands have been placed on the INS. Examples of some INSs and related components are shown and described in a brochure titled Implantable Neurostimulation Systems available from Medtronic, Inc., Minneapolis, Minn.
The effectiveness of the therapy as provided by the INS is dependent upon its capability of adjusting the electrical characteristics of the stimulation signal. For example, stimulation waveforms can be designed for selective electrical stimulation of the nervous system. Two types of selectivity may be considered. First, fiber diameter selectivity refers to the ability to activate one group of nerve fibers having a common diameter without activating nerve fibers having different diameters. Second, spatial selectivity refers to the ability to activate nerve fibers in a localized region without activating nerve fibers in neighboring regions.
The basic unit of therapy is a “therapy program” in which amplitude characteristics, pulse width, and electrode configuration are associated with a pulse train for treatment of a specific neurological conduction in a specific portion of the body. The pulse train may comprise a plurality of pulses (voltage or current amplitude) that are delivered essentially simultaneously to the electrode configuration. Typically, a pulse train is delivered to the patient using one or more electrode. The INS may be able to adjust the therapy program, for example, by steering the pulse train so that it affects desired portions of the neurological tissue to be affected. Alternatively, the INS may be able to adjust various parameters of the pulse train including, for example, the pulse width, frequency and pulse amplitude.
It is often desirable, however, for the INS to simultaneously provide multiple therapy programs to the patient. For example, it may be desirable to provide multiple therapy programs to treat the neurological condition being treated in various parts of the body. Alternatively, the patient may have more than one condition or symptom that needs to be treated. Moreover, multiple therapy programs could serve to provide sub-threshold measurements, patient notification, and measurement functions.
It is therefore desirable to provide an INS that is capable of delivering multiple independent therapy programs to the patient.